An electrophotographic image forming apparatus, such as, for example, a laser printer, a fax machine, or a photocopier, uses a light scanner to form an electrostatic latent image, coats the electrostatic latent image with a developing agent to develop the latent image into a visible image of one or more colors, and prints the same on an information transfer medium. That is, when light is scanned from a light scanner onto a surface of a photosensitive body pre-charged to a predetermined potential, the potential of a portion of the photosensitive body that is exposed to the light is changes so that an electrostatic latent image embodying the resulting potential difference may be formed on the photosensitive body. When toner particles move to the electrostatic latent image by electrical force, the latent image is developed into a visible image on the photosensitive body.
A light scanner typically includes a light source and a plurality of lenses that are disposed on the light path to the photosensitive body to variously refract or focus the light. Such lenses need to be assembled into their respective positions with accuracy in order to form an electrostatic latent image precisely on the photosensitive body. Such precision or imprecision may in turn affect the quality of the developed image.
Accordingly, to improve the image quality, the positional error in assembling the lenses may need to be minimized. The positional deviations may be amplified or exacerbated during use in an image forming apparatus whose internal temperature may fluctuate widely, for example, typically anywhere between 20° C. and 60° C. Thus, proper assembling of these lenses may be considered as an important factor in attempting to increase the image quality.